Henry Kelderman

Reconfigurable optical add-drop multiplexer using microring resonators

We report a reconfigurable four-channel optical add-drop multiplexer for use in access networks. The optical add-drop multiplexer (OADM) is based on vertically coupled thermally tunable Si/sub 3/N/sub 4/--SiO/sub 2/ microring resonators (MRs) and has been realized on a footprint of 0.25 mm/sup 2/. Individual MRs in the OADM can be tuned across the full free-spectral range of 4.18 nm and have a 3-dB bandwidth of 50 GHz.

Microresonators As Building Blocks For VLSI Photonics

In the last years much effort has been taken to arrive at optical integrated circuits with high complexity and advanced functionality. For this aim high index contrast structures are employed resulting in photonic wires in conventional index guiding waveguides or in photonic bandgap structures. In both cases the number of functional elements within a given chip area can be enhanced by several orders of magnitude: VLSI photonics. In this talk optical microresonators are presented as promising basic building blocks for filtering, amplification, modulation, switching and sensing. Active functions can be obtained by monolithic integration or a hybrid approach using materials with thermo‐, electro‐ and opto‐optic properties and materials with optical gain. Examples are mainly taken from work at MESA+.

Compact wavelength-selective switch for gigabit filtering in access networks

A compact [200/spl times/200 /spl mu/m/sup 2/] wavelength-selective switch based on thermally tunable SiO/sub 2/--Si/sub 3/N/sub 4/ microring resonators has been designed and realized. The switch supports gigabit filtering applications in access networks. Spectral measurements show an ON-OFF ratio of 12 dB and a channel separation of 20 dB. The 10-Gb/s measurements on a single ring show no degradation of the modulated signal and a theoretical BER (bit-error rate) <10/sup -12/.

Wavelength-selective switch using thermally tunable microring resonators

A novel wavelength-selective switch based on thermally tunable Si/sub 3/N/sub 4/ microring resonators has been designed, realized and characterized. The switch has an ON/OFF ratio of 7.5 dB and is made out of two rings which allow nearly full dropping (83%) and can thermally be tuned over 3 nm.

Ultracompact Optical Sensors based on high index-contrast Photonic Structures

There is a strong parallelism between electronic integrated circuits (ICs) and integrated optics. In both cases microand increasingly nano-technology is applied resulting in devices for a broad spectrum of applications: communication, data processing, sensing and others. The most striking difference is the maturity and complexity. Electronic ICs have followed Moores law for about 40 years resulting in the currently more than 100 million transistors in a single chip, whereas in photonic circuitries 10 100 functional elements per chip represent state-of-the-art results. Photonics in this respect is clearly lagging behind and will do so also in hture, as the minimum dimensions of the fimctional elements will be always in the order of the wavelen th of light, i.e. at least some hundreds of nm. But even then, F a density of 10 to lo5 functional elements per optical chip is feasible, so that the tenn Very Large Scale Integrated (VLSI) photonics1 is not an exaggeration. Optical circuits will not simple mimic electronics, but will exploit in a complementary way the unique phenomena offered by light. For example THz bandwidth amplification is straightforward in optical structures with

Bandpass filter based on parallel cascaded multiple microring resonators

A cascaded multiple microring resonators device exhibits a boxshape filter response and better isolation than a single microring resonator device. A parallel cascaded three microring resonator device has been realized in Silicon Oxynitride (SiON) technology to demonstrate functionality of the devices as a bandpass filter.

Characterization of Vertically Waveguide Coupled Microring Resonators by Means of Quantitative Image Analysis

The standard method of measuring the response of a micro resonator with in- and output waveguides consists of detecting the output power as a function of wavelength. In this paper a complementary method by means of quantitative image analysis is proposed. A vertically coupled waveguide microring resonator has been characterized with this method by projecting the scattered power of the device to an IR camera and analyzing the image as a function of wavelength. The reliability of this method has been confirmed by comparison with the standard measurement.

ULTRA-COMPACT SPECTRAL SLICER DEVICES BASED ON MICRORING RESONATORS

In Wavelength Division Multiplexing (WDM), access network spectral slicer devices in connection with a broadband light source are attracting low-cost alternatives for the laser diodes that are required for transmission in the desired wavelength channels. The proposed ultra-compact spectral slicer devices consist of microring resonators with slightly different radius and consequently slightly different resonant wavelength. Single and cascaded multiple microring devices have been fabricated and characterized to demonstrate the desired functionality. Cascaded devices show better performance in term of lower crosstalk, higher rejection ratio and faster roll-off. Moreover, they open the possibility to improve the spectral efficiency of the individual channels without introducing additional channel crosstalk.